cancelable Promise setTimeout() sample

asyncSetTimeout.js

function asyncSetTimeout(msec, func = () => {}){
    let timeoutId
    let r
    const exec = () => new Promise((res) => {
            r = res
            timeoutId = setTimeout(async () => {
                timeoutId = null
                await func()
                res()
            },msec)
        })
    return {
        exec,
        cancel: () => {
            if (timeoutId) {
              clearTimeout(timeoutId)
              timeoutId = null
              r()
            }
        }
    }
}

async function sleep(msec){
    return new Promise((res)=>{
        setTimeout(()=>res(),msec);
    })
}

console.log('start')

const func = async()=>{
    console.log('func start!!')
    await sleep(1000)
    console.log('func finish!!')
}

let cancel

(async ()=>{
    const a = asyncSetTimeout(1000,func)
    cancel = a.cancel
    await a.exec()
    console.log('finish')
})()


cancel()